In a typical wireless communication network, wireless devices, also known as mobile stations and/or user equipments (UEs), communicate via a Radio Access Network (RAN) to one or more core networks. The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” or “eNodeB” (eNB). A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole wireless communication network is also broadcast in the cell. One base station may have one or more cells. The base stations communicate over the air interface operating on radio frequencies with the wireless devices within range of the base stations.
A Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for wireless devices. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity. In some versions of the RAN as e.g. in UMTS, several base stations may be connected, e.g., by landlines or microwave, to a controller node, such as a Radio Network Controller (RNC) or a Base Station Controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
Specifications for the Evolved Packet System (EPS) have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base stations are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations, called eNodeBs in LTE, and the core network. As such, the Radio Access Network (RAN) of an EPS has an essentially “flat” architecture comprising radio base stations without reporting to RNCs.
All known small cell RBSs, for e.g. pico cells, are using combined transmission and reception antennas. A schematic block diagram for a first pico RBS is shown in FIG. 1. There is an antenna connector after a duplex filter to connect combined transmission and reception antenna as a product integrated antenna or external antenna arrangement to radio solution. In FIG. 1, one of two Multiple Input Multiple Output (MIMO) branches is merely shown as for clarity purposes. A RF board in FIG. 1 comprises a dedicated transmission (TX) chain with a power amplifier (PA), and a dedicated reception (RX) chain. Signals are processed in a Digital Signal Processing unit.
A Pico RBS may implement dedicated transmission and reception antennas into the RBS. E.g. the pico RBS may support multiple frequency bands in one Radio Frequency (RF) apparatus and a block diagram for a RF solution with a dedicated antenna arrangement is shown in FIG. 2.
Transmission (TX) and reception (RX) signals may be radiated from and to a radio apparatus e.g. an RBS, a Pico RBS, a Radio Dot System (RDS) or a wireless device with a coupled antenna arrangement and there may be dedicated transmission and reception antennas for the TX and RX signals, respectively, or one common antenna may be used to transmit and receive signals. In some radio apparatuses there is need for use dedicated TX and RX antennas to improve filtering characteristics between transmission and reception signals and thus improve radio performance of the receiver of the radio apparatus. Additionally, if an external antenna is connected to each dedicated RX and TX ports of the radio apparatus the number of needed antennas is duplicated. For example, a radio base station that supports two RF bands with 2×2 MIMO, with dedicated integrated internal RX and TX antennas needs eight antenna ports, i.e. 2×2×2 dedicated antennas. Dedicated RX and TX antennas are used to improve internal antenna isolation and thus improve filtering characteristics between the different signals.
The usage of a common antenna or a combined transmission and reception antenna has the advantage that it will reduce the number of antennas and antenna connectors by 50% and thus reduce the needed cabling for external antennas due to fewer antenna connections.
Today's radio apparatuses either use dedicated RX and TX antennas or a common antenna, providing nonflexible solutions once one antenna configuration is selected.